Why triple hop?
During many sports, it is unusual for an athlete to be required to make a single movement such as an isolated jump or hop.
Triple hop provides additional information about the patient’s ability to absorb and release energy during consecutive plyometric loading.
After #ACL reconstruction, at the time to return to sport athletes still have between limb differences for the knee work in all phases of a triple hop
Athletes shift the demands away from the injured leg – lower limb work absorption and generation is less in the injured leg in all phases. A possible mechanism to reduce lower limb loading is the adoption of an upper body compensatory strategy.
During both work generation phases of the triple hop, the relative contribution of the involved knee was significantly smaller, with a prominent compensation from the hip joint.
Despite passing the discharge criteria with flying colours, athletes still present significant knee work differences between limbs. Knee work differences were more prominent during work generation (concentric phase) than during work absorption (eccentric).
Still measuring hop distance?
Asymmetries in knee work during hops are not reflected in the hop distance.
Landing is the key!
Triple hop is probably the best to evaluate the ability of the knee to absorb high impact forces.
The GRF at the final landing is almost 3.5xBW!
Triple hop should be integral part of training after ACLR.
But using distance as discharge criterion is useless.
There ARE other metrics, more sensitive, to evaluate knee function....
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We measured athletes after #ACLR during propulsion & landing of a single leg hop for distance after they have been cleared to #RTS
During propulsion symmetry in work done by the knee is only 69% & during landing it’s 81%, despite achieving 97% of hop distance
The relatively large between-leg knee work difference is easy to miss as the knee joint contributes little (12%) to propulsion in a single hop for distance.
Hop testing after #ACLR – horizontal (distance) is easier to measure than vertical (height) but are they the same?
(Spoiler: not even close)
Thread 👇
During a vertical hop, the hip, knee, and ankle contribute almost equally, during push-off (height achieved) and landing (force absorption).
Horizontal hop is very different.
Work during propulsion (=distance achieved): knee contributes only 13% but the landing phase (absorption) is done 2/3 by the knee.